Public opinion against the FARC is widespread, and so is distrust in a rebel group that abused government efforts to negotiate peace between 1998 and 2002.

Back then, President Andres Pastrana created a demilitarized zone (larger in size than Switzerland) for the rebels to use as a haven. The FARC instead used the zone to build itself up militarily and carried out fearsome attacks until the talks broke down.

"Today, the conditions are very different," said Camilo Gomez, who as former high peace commissioner under Pastrana sat at the negotiating table.

"The FARC knows the time has come to make peace, and the government shouldn't be triumphalist, but knows there is a chance now for the public to accept (negotiations)," he said.

During the failed talks of a decade ago, the realities of both the government and the rebels were completely different, he said.

Colombia was facing a staggering economy, its military was woefully under-trained, attacks by rebels were at their most brazen and the government's own legitimacy was in question amid scandal.

In contrast, today the government is in a much stronger position, and the FARC has suffered a string of military defeats over the past several years.

Sooner or later, the moment for negotiation had to arrive, Gomez said.

Speaking on national TV, Santos said military operations would continue alongside any negotiations with guerrillas.

"Colombians can rest assured that the government is acting with prudence, seriousness and firmness -- always putting first the welfare and peace of all residents," the president said.

Santos hasn't elaborated on what shape the potential talks will take, but on Tuesday announced that Luis Eduardo Garzon, a popular former leftist mayor of Bogota, will play a key role.

On a radio program Tuesday, the president said that Garzon will have the rank of minister, though he will have a specific task.

"Now that we are entering into the possibility of having a peace process, we need a key person who can help us harmonize the people and teach and hold that important social dialogue," Santos said.

But the crassness with which the guerrillas disregarded and exploited the last opportunity still stings many Colombians.

"The government doesn't seem to have learned from history," said Alfredo Rangel, director of the Center for Security and Democracy at Sergio Arboleda University in Bogota.

"I think it's problematic that the government started negotiations with this terrorist group without asking first for it to stop all attacks on civilians," he said.

Santos, who is up for re-election in 2014, has seen his popularity plummet, and is foremost concerned with his political future, Rangel said.

Engaging in talks with the guerrillas is a desperate attempt to generate public support for his administration, he said.

It could backfire on the president, he warned: "There is enormous distrust in the guerrillas."

Rangel agrees with other critics who say peace talks are possible only if the FARC enforces a unilateral cease-fire. While the group has been severely weakened over time, it continues to carry out kidnappings and finances its operations through drug trafficking.

"That's easy to say, but difficult to do," said Gomez, the former peace commissioner.

Cynthia Arnson, director of the Latin American Program at the Woodrow Wilson International Center for Scholars, said a truce can come only from negotiations.

"A cease-fire is an outcome of negotiations, not a precondition," she said.

Santos has made ending the conflict a goal of his administration, and the challenge has been operating under conditions that are conducive for meaningful talks and not for a charade, Arnson said.

In recent years, the tide appears to have turned against the FARC, which the United States and European Union consider a terrorist group. In November of last year, the FARC's top leader, Alfonso Cano, was killed in a military operation in the country's southwest. He had been at the top of the guerrilla group since 2008, after its previous leader died of an apparent heart attack. That same year, Colombian security forces killed the then-second-in-command, Raul Reyes, during a cross-border raid into Ecuador.

Yet after all these hits, the FARC has not been defeated. In August of last year, the country's defense minister resigned amid growing concern about increased guerrilla activity.

"This seems an effort to take advantage of all the military successes, which have not utterly vanquished the guerrillas, and use those successes as a basis for ending the conflict that has dogged Colombia for more than half a century," Arnson said.

Among Santos' chief critics is former President Alvaro Uribe, a man Santos served under as defense secretary and with whom he was once close.

The two are now rivals, with Uribe on Tuesday accusing Santos of abandoning the nation's security in favor of negotiating with terrorists.

In a newspaper interview, Uribe said all Colombians want peace, but, "This dialogue was reached from a position of the resurgence of terrorism and not of the state's security achievements."

News of the preliminary talks come two months after the Colombian Senate overwhelmingly approved a constitutional amendment known as the "Legal Framework for Peace," which set the stage for eventual peace talks.

The amendment wasn't without controversy, as it limits prosecutions for war crimes or violations of humanitarian law to only a small group. Human rights activists feared it would allow abuses by the military and police to go unpunished, while those on the right said it would in effect grant amnesty to the rebels.

Any talks must include a measure of justice for the FARC, Rangel said.

Gomez said there are already models of transitional justice processes in other countries that show that human rights violators do not receive impunity.

Either way, said Arnson, for the peace process to have credibility, there will have to be visible changes on the ground by both sides.

"I think this is a right moment, but the difficulties are still huge," she said.

Gomez is not involved in the current talks, as he was a decade ago, and as an observer, he said the most important thing to understand is that the work is complicated.

What would he share with the men who sit at the negotiating table today?

"The best advice is not to give advice, and let the president act," he said.